This invention relates to mine safety equipment. More specifically, this invention relates to a method of and apparatus for constructing an escape shaft through which miners, otherwise trapped below the surface of the earth in mine shafts, tunnels or underground rooms, may be rescued.
How often is it that the newspapers have carried heart rending stories of miners, trapped in underground caverns by reason of explosion, flooding or similar reasons, and the frantic efforts being made to locate and rescue them? Even more disturbingly, how often is it that after days and weeks of search and rescue attempts, announcements are made that the rescue attempt was unsuccessful, the mine will be sealed and the miners entombed forever? The only answer to these questions is a single answer--all too frequently.
The problems attendant to rescuing miners trapped underground as a result of a mine emergency are legion. The first problem to be dealt with, of course, is locating the miners. Where were they in the mine when the emergency occurred? Would miners have been forced to move in order to escape immediate danger such as gas or flooding? Assuming that logical approaches can be taken with respect to these questions and a likely location of their wherebouts in the mine identified, where is this point in the mine with respect to a surface location in order that drilling may be commenced to establish communication with the trapped miners and ultimately to provide an escape route?
Each of the foregoing questions must be answered before significant on-site rescue operations may commence. They are significant in the consideration of the background relating to the present invention by reason of the fact that the development of responsive information to the issues which they present is time-consuming and a great deal of time is the one thing which mine rescue personnel do not have.
As will be recognized by those skilled in these procedures, once the likely location of the trapped miners has been identified and an appropriate point for the commencement of drilling in order to reach their location has been identified, drilling equipment and support equipment are positioned and the drilling of probe holes is commenced.
The purpose of the probe holes is to establish a relatively small diameter but adequate shaft through which to establish communication with the trapped miners, to provide ventilation air as required to the trapped miners and, if necessary, to provide basic essentials such as food, additional clothing, medical supplies and the like.
Once a probe hole has been drilled, it has been determined that the trapped miners are in the location suspected and their basic and immediate needs accommodated to the extent possible, immediate steps are taken to commence the drilling of an escape shaft. It is to the equipment for drilling, constructing and utilizing such an escape shaft that the present invention is addressed.
Those familiar with these arts will recognize quickly that the known prior art equipment for effecting a rescue once the location of miners has been determined has been woefully inadequate. Two fundamental approaches have been taken; the drilling of a bare-walled shaft to the site of the miners' entrapment and the construction of a lined shaft.
Utilization of the former approach has been found to be unacceptable not only in the industry but also to the Bureau of Mine Safety because the construction of such a bare-walled shaft creates as many problems as it solves. More specifically, the construction of a bare-walled shaft, i.e. merely drilling a hole down through the surface of the earth, gives rise to the possibility that the drilling of the escape shaft itself may result in flooding, may result in the introduction of toxic gasses to the place of entrapment of the miners or may otherwise give rise to conditions which are equally as dangerous if not more so than the conditions to which the miners are being subjected prior to rescue. Thus, the Bureau of Mine Safety and the industry has recognized that although the construction of a lined shaft takes more time than the construction of a bare-walled shaft, the reduction in the likelihood of creating additional emergency situations is of such significance and importance that the additional time taken to effect a rescue is deemed to be justifiable.
Such time, however, can be as much as an additional 24 hours added to the rescue mission. The attendant necessity of removing drill pipe from the drilled hole and thereafter lining the hole with casing is difficult, time consuming and often fatal. Thus, access to the area of entrapment for purposes of ventilating, dewatering, physical access and the like without the necessity for removing drill pipe and still without losing the benefit of a lined shaft is of primary importance and has heretofore not been achieved in these arts.